Plasma processing method and manufacturing method of semiconductor device

A plasma processing method of removing a deposit on a sidewall portion of a pattern of having metal layers in a stacked structure on a substrate, the method comprising:

• preparing the substrate with the pattern having metal layers in a stacked structure formed by dry processing, the stacked structure having a sidewall on a sidewall portion of which a deposit is deposited, the deposit containing at least one of metals of the metal layers;
• subjecting the stacked structure having said deposit to a protective layer forming step in which an oxide or chloride of the at least one of the metals is formed on the sidewall of the stacked structure having said deposit;
• applying a plasma of a gas containing fluorine atoms to remove the deposit;
• and
• applying a plasma containing hydrogen after forming the protective layer and removing the deposit, so as to reduce the oxide or chloride of the at least one of the metals.